@Override
public State nextState() {
// Receive message from client
Message msg = super.clientConnection.receiveMessage();
// Move straight to exit state if connection closed or invalid message
if (msg == null || msg.getMessageCode() == COD_EXIT) {
return endConnection();
}
// Ignore invalid messages
if (!this.isValid(msg)) {
errorNumber++;
logger.log(Level.INFO, "Invalid message received ({0})", errorNumber);
if (errorNumber >= INVALID_MSG_NUM) {
// End connection after too many invalid messages
return endConnection();
} else {
return this;
}
}
// reset counter
errorNumber = 0;
logger.log(
Level.INFO,
"Connected to: {0} ({1})",
new Object[] {msg.getUserAgent(), super.clientConnection.getSocket().getInetAddress()});
// Send handshake response with server version
Message response = new Message(msg.getReceiver(), msg.getSender(), "", COD_HELLO);
response.setUserAgent(Server.SERVER_VERSION);
boolean isSent = super.clientConnection.send(response);
if (!isSent) {
// End connection if sending failed
return endConnection();
}
// Move on to messaging state
return new MessageState(super.clientConnection);
}
private boolean isValid(Message msg) {
if (msg == null) {
return false;
}
if (msg.getMessage().length != msg.getMessageSize()) {
return false;
}
if (msg.getSender().length() < 1) {
return false;
}
if (msg.getReceiver().length() < 1) {
return false;
}
if (msg.getSendTime() < 0 || msg.getSendTime() > System.currentTimeMillis()) {
return false;
}
if (msg.getMessageCode() != COD_HELLO) {
return false;
}
return true;
}